A plurality of existing communication networks like the 3GPP communication networks, 2G/3G communication networks, and newly emerging SAE/LTE communication networks support the possibility to trace activities of users in the communication network. The users to be traced can for example be selected based on user identity (IMSI (International Mobile Subscriber Identity) based trace), terminal identity (IMEI (International Mobile Station Equipment Identity) based trace) or location (cell based trace). During tracing, all network activities related to the particular user can be logged and later on delivered to a central management entity of the communication network for evaluation. Logged network activities include for example signaling messages sent/received either on radio interfaces or network node interfaces.
Information obtained by tracing may for example be used to troubleshoot problematic user connections (e.g., in response to user complaints) or to monitor generic network performance and to perform root cause analysis to identify communication network problems. Nowadays, 3GPP communication networks offer the concept of “User Entity (UE) based network performance measurements”, also called, Minimization of Drive Test (MDT) measurements, in which measurements carried out by the UEs are used for network performance monitoring and optimization purposes. MDT measurements are carried out for states where the UE is connected (connection mode) to the communication network as well as for states where the UE is not connected (idle mode). The measurements where the UE is connected to the communication network are also called immediate MDT measurements since the UE reports the measurements when they are performed via legacy RRC (Radio Resource Protocol) protocol mechanisms, i.e., there is no internal logging in the UE. The measurements where the UE is not connected are also called logged MDT measurements since the MDT measurements are collected and logged in the UE; in this case, the collected MDT measurements are reported to a network node of the communication network in a bunch as soon as the UE is connected to the communication network again (logged reporting in idle mode is necessary since the UE does not have an active connection to the network in idle mode and thereby cannot report the measurements at the time when they are taken).
In order to manage MDT UE measurements in 3GPP communication networks, trace functionality is used. This means that a network management system which manages the communication network can configure and collect measurements using trace methods.
In current 3GPP communication networks there are two ways to activate tracing, namely “signaling based activation” or “management based activation”. In signaling based activation, the trigger for tracing a particular user (UE) is propagated piggy-backed on a regular UE-specific signaling message sent between the network nodes through which a user flow passes. Initially, the network management system configures tracing of a particular user (UE) in a HSS (Home Subscriber System) or in core network nodes (e.g., MME, SGSN (Serving GPRS Support Node)) based on the user IMSI or IMEI. As soon as the user with the given IMSI or IMEI appears in the communication network, and the HSS, MME or SGSN etc. is interrogated for user information (e.g., security credentials at a user attach), a trace trigger will be propagated to related network nodes via the invoked signaling flow. In management based activation, the trace trigger is not propagated to other network nodes. The management system configures selected network nodes to trace a particular user or set of users. When a new user appears at a network node, the network node evaluates a selection criteria and starts trace recording in case the condition is satisfied.
In current communication standards, if MDT measurements are taken using trace collection, the concept of “user consent” has to be taken into account (for privacy reasons). The concept of user consent provides a control for the user to allow or reject the collection of MDT measurements. The consent for MDT measurement collection is stored as part of subscription data, and when no positive user consent is available for a particular user, the communication network is not allowed to initiate MDT measurement collection for that user. This applies both for IMSI based measurement collection and cell based MDT measurement collection. Moreover, no user identity, i.e., IMSI or IMEI information is allowed to be sent to a TCE in case of an area based MDT measurement collection, not even if a user consent is available. This means that only the trace session ID and trace recording session ID are provided to the TCE together with the trace records, but no information which would allow to map the MDT measurements to unique user identities. Further, in the case of cell based tracing, a trace session ID and a trace recording session ID are changing when the UE switches from one cell to another cell. Similarly, different trace IDs are assigned to different trace jobs. Also, in current communication standards, a separate trace job type is defined for the collection of Radio Link Failure (RLF) reports, for which the user consent does not apply. All RLF reports received from UEs directly (or via neighbor cells on X2) are collected and reported in one single trace session. In this case there is no possibility to identify which user has generated the RLF report.
In view of the above circumstances, the value of the collected MDT measurement information is decreased since it is not clear to which user the collected MDT measurement information belongs.